In die-casting and injection molding machines a ram device is provided for injecting the molding material into the mold. This ram device, in one case, can be formed by an injection piston, or in another case by an injection screw actuated in a piston-like manner. For moving this ram device, drive means are provided, generally formed by an injection drive, and in some cases with an intensifier or booster piston. The above-mentioned housing or sleeve is, in the case of a die-casting machine, formed by an injection or shot cylinder, or--in injection molding machines--by a screw barrel.
Such machines often have a pressure transducer for determining the pressure, and the signals of the transducer are used for control or indicating purposes. The pressure transducer frequently comprises two pressure sensors arranged on the drive cylinder for determining the differential pressure. Moreover, there is a position transducer and a timer by which the velocity of the ram may be determined. A machine with these transducers and a timer is described in the German Patent No. 3,142,811.
Where a high productivity and quality of the molded products was required, already heretofore the maximum injection power heretofore has been predetermined once and for all in a laboratory test. Perhaps that one informed himself later in a further laboratory test, to know in which range the actual power of the machine could be. The measurement under laboratory conditions did not meet, however, the rough conditions of the workaday in a factory, on the one hand, whereas on the other hand disturbances and interferences of different kind could lead to substantially exceeding of the predetermined theoretical "actual" injection power. Therefore, the parameters of the machine had to be preadjusted from the beginning in such a manner that the actual injection power was apropriately below the possible maximum nominal injection power. In this way, it was no longer feasible to attain a high percentage of the nominal injection power.